V. N. Matveev

Size effect relating to the extraordinary and the ordinary Hall effect in ultrathin Fe-Pt films

An experimental study is presented on the extraordinary and the ordinary Hall effect in ultrathin Fe-Pt films down to 1.5 nm thick deposited by laser ablation in a high vacuum. The variation of the Hall coefficients with film thickness is investigated. It is shown that the extraordinary Hall coefficient varies as film resistivity and grows with decreasing film thickness. The extraordinary and the ordinary Hall coefficient are found to depend on the substrate material.

Peculiarities of the extraordinary Hall effect of planar arrays Fe nanoparticles embedded in an ultrathin Pt film

The extraordinary Hall effect was investigated for planar arrays Fe nanoparticles embedded in an ultrathin Pt matrix. It was found that the slope of Hall resistance (RH) reversed sign at ±0.15T for Fe particles of mean thickness 0.3nm. The dependence is presumably due to the effect of two spin-orbital induced mechanisms of carriers scattering, skew scattering, and side jump, with the skew component of positive sign and the side jump component of negative sign. For Fe samples, 0.6nm thick RH increases monotonically with the magnetic field value. At low temperatures, the superparamagnetism of the samples disappeared.

Relationship Between Structure and Electromigration Characteristics of Pure Aluminum Films

Aluminum films were deposited from a high purity aluminum source by the self-ion assisted technique onto oxidized silicon wafers with TiN sub-layers. The ions were accelerated toward the substrate by potentials of 0, 3 and 6 kV. The films were patterned into strips 670 μm long and 8 μm wide using photo-lithographic procedures and wet etching. Average drift velocities were measured in the films tested under electromigration conditions. Electromigration activation energy was obtained for the films. It was found that electromigration activation energy increased with the acceleration potential. The strength of the (111) fiber texture, however, decreased with the acceleration potential. Therefore, the weaker textures resulted in higher electromigration activation energies. These results can be explained in terms of grain boundary structure, which controls electromigration behavior. By using orientation imaging microscopy to characterize the structures, it was shown that the weaker textured specimens contained a high fraction of low angle and low diffusivity grain boundaries.

Extraordinary Hall effect in planar ensembles of Co nanoparticles embedded in Au or W

An experimental investigation is presented into the extraordinary Hall effect (EHE) in planar ensembles of Co nanoparticles embedded in a W or Au matrix. The EHE signal strength is shown to depend on the mean thicknesses of both the nanoparticles and the matrix. Its maximum is observed for mean Co thicknesses of 0.3–0.6 nm. The EHE signal is found to grow with decreasing matrix thickness until the structure loses its electrical continuity. A sensitivity as high as S = 32 Θ/T (S = ΔU/IΔH) is achieved with a Co-W film. This result opens up possibilities for building room-temperature ferromagnetic sensors for local magnetometry.

The energy of activation of electromigration in aluminum conductors tested by the drift-velocity method

Electromigration in pure aluminum films evaporatively deposited with the method of partially ionized flux was studied by the drift-velocity technique. In annealed films, the energy of activation of electromi-gration was found to be almost half as large as in as-deposited ones. The film structure and texture, as well as the grain-boundary structure, were examined. The electromigration front morphology and activation energy variations were analyzed in the context of film structure.

One-Step Synthesis of a Hybrid of Graphene Films and Ribbons

Hybrid structures composed of graphene films and (0001) graphene ribbons perpendicular to the surface of a graphene-like film have been produced through the catalytic decomposition of a carbon-containing gas on an Al-coated SiO2/Si substrate having Ni catalyst islands on its surface. A hybrid structure has been grown by a one-step chemical vapor deposition process, by admitting acetylene into a chamber for a short time. The hybrid structures thus produced have been used to fabricate Hall sensors with a sensitivity of 3000 Ω/T. The synthesized hybrid structures are potential candidates for use in nanoelectronic devices, energy storage systems, etc. The technique proposed for the growth of such films is compatible with technologies that are employed in the electronics industry.

Using a nanoscale extraordinary hall effect sensor to measure the tip field of a magnetic cantilever

The spatial distribution of the magnetic field around the tip of a magnetic cantilever coated with a cobalt film 50 nm thick is investigated using an FePt extraordinary Hall effect sensor. The magnetic field’s dependence on the distance between the sensor’s surface and the MFM cantilever is measured and found to be inversely proportional to the cubic distance, as predicted in theory. The magnetic field measured on the MFM cantilever tip is found to be 0.02 T.

Texture and microtexture of copper films prepared by the self-ion assisted deposition technique on barrier layers with different structure

Cu may diffuse into the active areas of semiconductors resulting in degradation of the devices. Therefore Cu is isolated from silicon wafers by barrier layers. In this study, copper films were deposited onto silicon substrates coated using polycrystalline Ta 3 N 5 and amorphous α-C:H barrier by the partially ionized beam deposition technique at 6 kV bias, to investigate an influence of barrier layer structure on texture and microstructure of Cu films. After deposition, films were annealed under vacuum. Texture of the films was studied by X-ray diffraction and further microstructural analysis of the copper films was performed by orientation imaging microscopy. Results of the structural analysis reveal large (100) grains in films deposited on α-C:H barrier layer and a bi-modal texture in films on Ta 3 N 5 .

Em activation energy in aluminum conductors tested by the drift velocity method

TexSEM Laboratories, Draper, UT USA(Received October 14, 1999)(Accepted October 27, 1999)Keywords: Ion beam methods; Electron diffraction; Electromigration; Grain boundariesIntroductionElectromigration (EM) resistance of aluminum conductors is one of the major factors determining thereliability of modern integrated circuits (ICs), especially in connection with the reduction of conductorwidth to values below 0.5 microns. Therefore an understanding of EM processes and failures willpromote the development of new interconnect technologies which will ensure reliability satisfyingmodern requirements. The drift velocity method [1] for EM research in thin film conductors wasdeveloped by Blech in the mid-1970’s. This method allows the most authentic determination of the EMcharacteristics of metal films [2]. A schematic illustration of the method is presented in Figure 1. Thestrip of tested metal lays on a film from a material with higher resistance, as a rule TiN or Ta. Whenelectrical current passes through the pair it is shunted by metal with higher conductivity. Owing to EM,the material will move from the cathode end and will accumulate on the anode end of the strip. Theassumption that the average drift front is equal to the average ion velocity, allows one to obtain anestimate of the EM activation energy.Researching EM by the drift velocity method, researchers have found that two cases can occur. Oneis when residual material is left behind the drifting front [3–7], and other is when no material is leftbehind [8–10]. The theory of slot-like groove propagation was offered by Glickman [11]. This theoryexplains the origin of the residual material observed behind the drifting edge of the strip. The modeldescribed in that work relates EM drift velocity and the residual mass left behind the trailing end to thegroove propagation rate and groove width, respectively. Only this case will be considered in the presentwork.Under typical service conditions of IC’s or in any accelerated testing conditions the EM flux isconcentrated along grain boundaries. The depletion of matter from grain boundaries must be accom-modated by a diffusion flux providing matter into grain boundaries from adjacent grains. At theconditions under consideration bulk diffusion is insignificant. Surface diffusion along the walls andgrain boundary grooves plays the primary role.If surface diffusion is fast and provides a rapid transfer of matter from the surface of the adjacentgrains to the groove tip then grain boundary diffusion is a rate controlling process in groove